In the past, brittle fracture of steel structure was reported rarely under earthquake. However, recent earthquakes, especially Northridge Earthquake (USA) and Hyogoken Nanbu earthquake (Japan), astonished engineers i...In the past, brittle fracture of steel structure was reported rarely under earthquake. However, recent earthquakes, especially Northridge Earthquake (USA) and Hyogoken Nanbu earthquake (Japan), astonished engineers in the field of construction. The experience from recent earthquakes of USA and Japan shows that brittle fracture of welded steel structure always starts from high stress zone with welded crack [1～5] . As backing bar for grooved weld on beam flange exists, artificial crack is formed because of lack of fusion at the root of flange weld. In this paper stress distribution of connection is computed with FEM, and stress concentration at the root of flange weld is also analyzed. Stress intensity factors (SIFs), K I, at the root of flange weld are computed in the method of fracture mechanics. The computation shows that stress intensity factor on bottom flange weld is obviously higher than that on top flange weld. It is proved by the fact that brittle fracture is liable to start at the root of bottom flange weld on actual earthquake [1,4] . Finally measures are brought forward to avoid fracture of weld structure against earthquake.展开更多
为了研究砌体开裂过程的力学行为,提出利用现代计算机技术的数值试验方法,将砌体看成是由块体、砂浆和二者间的黏结带构成的三相复合材料,采用最大拉应力准则和摩尔库仑准则作为损伤本构关系的损伤阀值,建立砌体开裂数值模型,应用复合...为了研究砌体开裂过程的力学行为,提出利用现代计算机技术的数值试验方法,将砌体看成是由块体、砂浆和二者间的黏结带构成的三相复合材料,采用最大拉应力准则和摩尔库仑准则作为损伤本构关系的损伤阀值,建立砌体开裂数值模型,应用复合材料破裂过程数值分析系统MFPA2D(M aterial Failure Process A-nalysis),从应力场活动图像出发,模拟了砌体受压试件从损伤到开裂破坏的力学行为.研究表明,数值试验结果与试件物理实验结果较为吻合,为砌体开裂机理研究和发展、砌体力学性能研究提供了新的技术路径.展开更多
文摘In the past, brittle fracture of steel structure was reported rarely under earthquake. However, recent earthquakes, especially Northridge Earthquake (USA) and Hyogoken Nanbu earthquake (Japan), astonished engineers in the field of construction. The experience from recent earthquakes of USA and Japan shows that brittle fracture of welded steel structure always starts from high stress zone with welded crack [1～5] . As backing bar for grooved weld on beam flange exists, artificial crack is formed because of lack of fusion at the root of flange weld. In this paper stress distribution of connection is computed with FEM, and stress concentration at the root of flange weld is also analyzed. Stress intensity factors (SIFs), K I, at the root of flange weld are computed in the method of fracture mechanics. The computation shows that stress intensity factor on bottom flange weld is obviously higher than that on top flange weld. It is proved by the fact that brittle fracture is liable to start at the root of bottom flange weld on actual earthquake [1,4] . Finally measures are brought forward to avoid fracture of weld structure against earthquake.
文摘为了研究砌体开裂过程的力学行为,提出利用现代计算机技术的数值试验方法,将砌体看成是由块体、砂浆和二者间的黏结带构成的三相复合材料,采用最大拉应力准则和摩尔库仑准则作为损伤本构关系的损伤阀值,建立砌体开裂数值模型,应用复合材料破裂过程数值分析系统MFPA2D(M aterial Failure Process A-nalysis),从应力场活动图像出发,模拟了砌体受压试件从损伤到开裂破坏的力学行为.研究表明,数值试验结果与试件物理实验结果较为吻合,为砌体开裂机理研究和发展、砌体力学性能研究提供了新的技术路径.
